import json
from twisted.internet.defer import inlineCallbacks, returnValue

from .wormhole import wormhole


@inlineCallbacks
def receive(reactor, appid, relay_url, code, use_tor=None, on_code=None):
    """
    This is a convenience API which returns a Deferred that callbacks
    with a single chunk of data from another wormhole (and then closes
    the wormhole). Under the hood, it's just using an instance
    returned from :func:`wormhole.wormhole`. This is similar to the
    `wormhole receive` command.

    :param unicode appid: our application ID

    :param unicode relay_url: the relay URL to use

    :param unicode code: a pre-existing code to use, or None

    :param bool use_tor: True if we should use Tor, False to not use it (None for default)

    :param on_code: if not None, this is called when we have a code (even if you passed in one explicitly)
    :type on_code: single-argument callable
    """
    wh = wormhole(appid, relay_url, reactor, use_tor)
    if code is None:
        code = yield wh.get_code()
    else:
        wh.set_code(code)
    # we'll call this no matter what, even if you passed in a code --
    # maybe it should be only in the 'if' block above?
    if on_code:
        on_code(code)
    data = yield wh.get()
    data = json.loads(data.decode("utf-8"))
    offer = data.get('offer', None)
    if not offer:
        raise Exception(
            "Do not understand response: {}".format(data)
        )
    msg = None
    if 'message' in offer:
        msg = offer['message']
        wh.send(json.dumps({"answer": {"message_ack": "ok"}}).encode("utf-8"))

    else:
        raise Exception(
            "Unknown offer type: {}".format(offer.keys())
        )

    yield wh.close()
    returnValue(msg)


@inlineCallbacks
def send(reactor, appid, relay_url, data, code, use_tor=None, on_code=None):
    """
    This is a convenience API which returns a Deferred that callbacks
    after a single chunk of data has been sent to another
    wormhole. Under the hood, it's just using an instance returned
    from :func:`wormhole.wormhole`. This is similar to the `wormhole
    send` command.

    :param unicode appid: the application ID

    :param unicode relay_url: the relay URL to use

    :param unicode code: a pre-existing code to use, or None

    :param bool use_tor: True if we should use Tor, False to not use it (None for default)

    :param on_code: if not None, this is called when we have a code (even if you passed in one explicitly)
    :type on_code: single-argument callable
    """
    wh = wormhole(appid, relay_url, reactor, use_tor)
    if code is None:
        code = yield wh.get_code()
    else:
        wh.set_code(code)
    if on_code:
        on_code(code)

    wh.send(
        json.dumps({
            "offer": {
                "message": data
            }
        }).encode("utf-8")
    )
    data = yield wh.get()
    data = json.loads(data.decode("utf-8"))
    answer = data.get('answer', None)
    yield wh.close()
    if answer:
        returnValue(None)
    else:
        raise Exception(
            "Unknown answer: {}".format(data)
        )